The present invention relates to a method of preparing a mold surface for use in applying a facing composition to a substrate and to an improved mold useful in carrying out the substrate facing operation. More specifically, the present invention relates to an improved mold surface texturing process whereby a desired texture or pattern can be imported to the molded article without interfering with the color of the facing composition to be applied to the substrate but will impart a pleasing texture to the substrate facing composition.
In the art of applying decorative facing compositions to substrates such as building blocks, tiles or other construction articles, it has been desired to impart texture to the facing compositions in order to improve the appearance and "feel" of the applied surface. In the past, expensive and time consuming variations in the formulation of the facing composition material has been required in order to achieve any variations in the surface appearance or texture other than color of the facing composition. Thus, the uniformity of the appearance and texture of the facing compositions on the construction blocks or other materials to which the facing compositions are adhered has limited their use to certain environments since only a smooth, glaze-like surface texture could be achieved. Glazing compositions with which the present invention is particularly useful are disclosed in U.S. Pat. Nos. 4,031,289, 2,751,755, 3,328,231. U.S. Pat. No. 4,031,282 discloses a particular method of applying a decorative surface to obtain a desired appearance on a construction panel. Other coating compositions are disclosed in U.S. Pat. Nos. 3,194,724, 3,078,249 and 3,030,234. U.S. Pat. No. 4,533,568 discloses a method of treating a mold surface to impart a selected pattern to the molded composition in applying the composition to a substrate such as a masonry unit. The disclosures of the foregoing patents are incorporated herein by reference.
The present invention provides a method of preparing a mold surface and a mold itself which can more readily and expeditiously obtained to provide a unique texture to the facing composition at the time the facing composition is applied to a substrate such as a masonry unit including a cement or cinder block or tile member.
In a preferred embodiment, the mold surfaces of a conventional molding unit such as a shallow metal pan are first coated with a conventional enamel composition such as glass enamel or porcelain frit. Prior to fusing of the enameling composition, particulate material such as sand particles having a desired average screen size which may be varied to provide different effects in the resulting product are distributed either uniformly or in a random pattern over the bottom surface of the unfired enameling composition. The mold is then fired to fix the particulate material in place and harden the first coating. Subsequently, a second thin layer of the same or a different enameling composition is coated over the particulate material. The resulting compositely coated mold unit is then subjected to a final firing step such as by kiln drying.
The mold is then used in a conventional manner in the application of a decorative facing to a substrate such as a masonry or construction unit and will result in the formation of a pleasing texture to the facing composition, particularly those of the type disclosed in the foregoing commonly assigned patents.
From the description that follows, it will be apparent that the present invention provides a very economical method for either altering a previously coated mold or manufacturing a new mold element for applying a desired pattern or texture to a facing composition In addition, previously employed conventional ceramic or enamel coated mold units can be readily adapted at minor expense in terms of labor and time so as to be able to impact a desired texture to a facing composition even where such mold units have been partially damaged or defaced such as by cracking, grazing or the like.
The foregoing and other advantages will become apparent as consideration is given to the following detailed description taken in conjunction with the accompanying drawings, in which: